Stephen Cruz changed his route because he was tired, and he didn't regret it, and he accidentally found a piece of a spine 15 cm long by the North Salfer River, about 130 km north-east of Dallas, U.S.A.
100 meters from him, he found the rest of the fossil bones that belong to the puzzle, a huge 10-metre-long sea lizard that lived in the seas about 80 million years ago.
Recently, paleontologists from the Museum of Nature and Science, Pero, dug up fossils from a soft, clay-like rock of a stream, and they dug up parts of the brain of the puzzle, the bones of the lower jaw, and several vertebrae.
This is an important work for scientists: though the puzzles are extinct, the study of their past can give us an opportunity to look into the present. If we understand what ancient creatures were eating and how they interacted with the environment, it will help paleontologists to learn more about what life was like millions of years ago.